Rail clamp for traveling bridges



June 17, 1930. B. H. KERSTING RAIL CLAMP FOR TRAVELING BRIDGES 6 Sheets-Sheet l v Fifed June 19, 1924 June 17, 1930. B. H. KERSTING I RAIL CLAMP FOR TRAVELING BRfDGES Filed June 19, 1924 G Sheets-Sheet 2 INVENTOR.

June- 17, 1930. ERS ING' 1,764,797

RAIL CLAMP -FOR TRAVELING BRIDGES Filed June '19, 1924 a Sheets-Sheet 5- I! V v ZII/NVVEATOR I f June 17, 1930,

K ERSTING- 1,764,797

RAIL CLAMP FOR TRAVELING BRIDGES I Filed June 19, 1924 6 Sheets-Sheet 5 tmiosaou HAT INVENTOR June 17, 1930. B. H. KERSTING 1,764,797

RAIL CLAMP FOR TRAVELING- BRIDGES Filed June 19, .1924 6 Sheets-Sheet 6 Canfral/er 67 6] i 62 n A To Brie/q: ,C'onfrol/er 6 Z L E; 77; Bridge Canhpl/er INVENTOR Corresponding truck 5.

Patented June 17, 1930 i to re s BERNARD I-I. KERSTING, 01? BEN AVON, PENNSYLVANIA, ASSIGNOR TO THE DRAVO CONTRACTING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA RAILOLAMP FOR TRAVELING BRIDGES Application filed June 19,

The present invention relates to rail clamps for traveling bridges, a preferred embodiment of the invention'being illustrated in the accompanying drawings, in which Figure'l is a side elevation of a traveling bridgeto which the invention is applied;

Figures 2 and 3 are sec'tionson the lines TI -IT and IH-TH, respectively, of Fig ure 1, looking in the direction of the arrows; 1

Figure 4 is a view in elevation, on a larger scale, showing the rail clamp mechanism which is associated with each leg of the bridge;

Figure 5 is a broken plan view of the mechanism shown in Figure 4;

Figure 6 isan end view of the structure shown in Figures 4 and 5, looking from the right, showing the clamping levers of one of the rail clamps in closed position;

Figure 7 is a section on the line VIIVII of Figure 4 showing the clamping levers in open position 3 Figure 8 is a detail View of a yoke member; Figure 9 is a detail view of an equalizer pin; V

Figure 10 is a detail view of ayoke pin, and 1 Figures 11, 12, 13 and 14 are wiring diagrams;

Referring to Figures 1, 2 and 3, the nuineral 2designates traveling bridge having legs 3and 4 carried on trucks whichmove along theftracks 6. This bridge is provided with the usual clanishell bucket 7 and operators cap 8. Associated with. each truck is a. rail clump mechanism 9 embodying my invention.

As will be apparent by reference to Figures 4 and 5, each clamp mechanism comprises two separate rail clamps l0 and 11 controlled by a single electric motor 12 mounted on the The motor has a pinion 13 on its armature shaft meshing with a gear 14carriedon one end of a shaft 15 journaled in the truck. Carried on the other endof this shaft is a pinion 1.6 meshing with a gear 17 on one end'of the drum shaft 18. Carried on the other end of this shaft is a drum 19 around which a' cable 20 winds. The cablepasses around the sheaves 21' and 22 of 1924. Serial No. 721,066.

the clamp 10 and has its end 23 looped about a cable anchor 24 in the form of a grooved pulley carried bythe pin 25 of the sheave 22. The pin 26 of the sheave 21 is carried in brackets 27.

The clamps 10 and 11 are exactly alike in construction and operation so that a detailed description of the clamp 10 will suffice,the

parts of clampll being designated by the same reference numerals as corresponding parts of the clamp 10. The clamp 10 comprises a pair of rail clamp levers 28 and 29 bifurcated at their upper ends to straddle the sheaves 21 and 22 and pivoted upon the sheave pins 25 and 26. These levers carry at their lower ends clampjaws 30 adapted to grip the sides of therail 6. The levers are connected adjacent their lower ends by links 31 which are pivotally connected thereto by the pivot bolts 32. These bolts extend through slots 33 in reinforcing plates 34 and channels 35. The reinforcing plates and; channels are rigidly connected at their endsin any appropriate manner to angles 36 se cured to side plates 37 depending from the connecting links 31' and. the sides of this housing, for a purpose which will be explained hereinafter.

Pivoted upon the sheave pin 26 at the outer sides ofthe bifurcated upper end of the clamp lever 28 are bell cranks 42; Each bell 9o crank is pi'votally connected at one end to a screw clevise '43, the latter being adjustably. connected to an eye-bolt 44. The eye-bolts are pivoted upon the sheave pin 25 at the outer sides of the upper bifurcated end of '95 the crank lever 29 and the adjustment be tween the eye-bolts and clevises is maintained by lock-nuts 45.

' The bell cranks 42 are pivotallyconnected at the other end to one end of a yoke 46; The lot The angles 36, side plates 37, 30

yoke is connected at its other end to an equalizer slidably mounted between guides 100. This equalizer consists of parallel plates 47 spaced apart by spacers 48. Journaled between said plates centrally thereof is an equalizer pin 19. This equalizer. pin has a bore through which extends a yoke pin 50. The yoke pin has its ends fixed in the bifurcated ei' t-rein-ity otthe yoke. The bifurcated e-Xtren'nty of the yoke is rounded and housed in a spring box {SS-mounted on top of thetruckb. Each spring abuts at one end againsta plate 54, held on the free end of the corresponding spring red by a nut 55, and at the other end against aiixed portion'ot the spring box. The spring rods 51 are each provided with nuts 51 on that portion of the rod 51 projecting beyond the fixed portion of the frame against which the spring. 52 abuts. These nuts act as positive stops for limiting the range of effective operation of the s pring and theyare of decided importancc for two reasons. 11' the clamp jaw sl'iould'ha gipen' to wear to a point wheregripping could be eiiected only by undue expansi'onof the springs 52 the nut 51 will bear against-the-spring box and the operator will thus :be warned that he must adjust the portions -13 and 1 1 of the to le arm in order to take up the wear. A further advantage is that the nuts permit the disassembling of the connectingme-ans between the rod 51 and the clamp jaw propel-without entirely releasing thespring. from the initial load which is-iniposed thereon in order that the springs exert the desired closing force at the limit or their operating travel.

A cable/56 also-winds on the drum 19 and extends therefrom over a sheave 57 mounted on the housing of the clamp 11 andthen passes'around the sheaves 21 and 22 of the latter clamp and has its end 58 looped around a cab'le anchor 2% on the sheave pin 25.

soclated with the sheave is a cable guard When the drum '19 is rotated in a direction to. windTth'e cables 20 and thereon, the sheaves 22 of the clamps'lO and 11 are moved towards the sheaves 21, thereb rocking the clamping levers2-9 on their-pivots 32 to disengage their clamp jaws 30 from the rails.

After'th'e beveled edges d1 of said levers engage the edges of the horizontal flanges of the angles 39, further rocking movement of the levers 29 takes place about the points of engagement of said beveled edges with said flanges and causes the clan'iping jaws of the levers 28 to be backed away from the rails through the links 31. This movement is permitted by reason of the clearance between the ends of the links 31 and the sides of the housings for the clamp levers and also by reasonofthe slots in the reinforcing plates 34 and channels 35 through which the ends of the pivot bolts extend. The relative movement of'the upperextremities of the clamp levers towards each other causes the toggles 424l3 dd to move from the position shown in Figure 6 to that shown in Figure 7, thereby rocking the bell cranks 42 ina clockwise direction and putting the springs 52 under tension. When'the circuit of the motor 12 is opened these springs immediately move the clamp levers back into the position shown in Figure 6, in which the rail is gripped by the clamp jaws. During'the closing of the clamps, the levers 29 are rocked about their pivots 32 until the clamp jaws 30 at the lower ends of the levers engage the rails. Thereafter, the clamp jaws 30 at the lower ends of the levers 28 are pulled into engagement with the rails through the links 31.

Associated with the clamp 10 of each clam-p mechanism 9 is a pair of limit switches 61 and 62, as shown in the wiring diagrams of F igures'll, 12, 13 and ll. These switches are located in ahousing 60 carried by supports 101 and are adapted to be operated in unison by a lever 63 in such manner that when one switch is closed thexother is opened, and vice versa; The lever 63 is pivoted to the hatchway at 64 and has its outer extremity bifurcated, a roller 65 being journaled in this bii'flllClttBCl extremity. The upper plate 47 of the corresponding equalizer has a beveled edge 66 for cooperation with this roller. In the closed position of the clamp 10, as illus trated in Figure 6, the equalizer is out of contact with the roller 65 and the limit switch 61 is closed and the limit switch 62 open, as shown in Figures 11 and 13; When the clamp has been moved to open position, however, the equalizer is in the advanced position shown in Figure 7, in which the roller 65 is held thereby in raised position. In this position of the parts, the switch 61 is open and the switch 62 is closed, as shown in Figure 12.

Figures 11, 12 and 13 are wiring diagrams of either motor '12, and Figure lelis a combined wiring diagram of both motors. Referring to these wiring diagrainathe two motors 12 of the clamp mechanisms 9 for the two legs of the bridge are connected in parallel with the feed lines and are adapted to be controlled by 'a foot-operatedswitch 67 located in the operators cab, said switch being normally open, as illustrated in Figure r 13. lVhen the operator desires to move the closing -Furthermore, the provision ot a pair of bridge, he closes the foot switch. This complctes a circuit through the magnet coils 68 i and 69 and causesthe contact 7 O toclose and the contact 71 to open, as shown 1n Figure 11. The closing of the contact 7 O completes a circuit through the magnet coil 7 2, causing the contact 73 to close also. The closing of the contacts and 73 closes the motor circuit through the resistances R and R The motors are then operated simultaneously to turn the drums-19 in a direction to wind the cables 20 and 56 thereon, thus opening the clamps. lVhen the clamps have been moved to fully open position, the limit switches 61 of the two clamp mechanisms are open and the limit switches 62 closed, as illustrated in Figure 12, by reason of the engagement bf the equalizers of the clamps 10 with the rollers 63. The opening of the limit switch 61 of either motor breaks the circuit of the contact 73 thereby causing said contact to open'and cut the resistance R into the motor circuit. This stops the motors 12 but passes sufficient current through them to hold the clamps open against the tendency of the springs 52 to close them. It will be apparent, by reference to Figure 14,

that since the limit switches 62 of the two motors are connected in series in the circuit or" the controller for the bridge traversing motor, the bridge cannot be moved until both clamp mechanisms 9 have been fully opened. Then the operator removes his foot from the switch 67 the latter opens, thereby breaking themotor circuits, and the springs 52 immediately move the clamps into engagement with the rails, at the sametime running the motors 12 backward; Then the switch 67 is open the contacts 7 1 are closed, so that the motors are driven backward on dynamic brake resistances R.

By the present invention I have provided an extremely efficient rail clamp mechanism which, due tothe simplicity of its construction, is relatively inexpensive to manufacture and install. This clamp mechanism insures the clamping of the rails in case one ofthe cables should happen to break, for the reason that the cables are employed for opening the clamps and springs are employed for closing them. By reason of the toggle arrangement between thesprings and the clamp levers, the springs are enabled to exert a powerful force upon the clamp levers.

springs for each clamp connected to the clamp levers through an equalizer and atoggle mechanism, renders it unnecessary to employ partlcularly heavy springs, It will be noted that the toggle arrangement is such that its'mechanical advantage with respect to rail clamping increases as the jaw moves toward the rail. This is highly desirable because the spring means employed for clos ing the jaws inherently provides a decreasgle'and spring so that the mechanical ad vantage of the toggle varies inversely with thepower of the spring is also important on the jaw opening step. Qnce the clamping jaw is clear of the rail, it is desired to do as little work as possible in order to maintain] the jaws in open position. Considering the toggle from this point of view it willbe ap: parent thatthe toggle provides means where by a decreasingly small force is required for opening the jaws. This means of course that less eiiort -will be expended in maintaining the jaws open so that the toggle when combined with the spring in a manner herein provided is of decided importance whether the jaws are being opened or closed. By connecting the limit switches of the clamp mechanisms for. the two legs of the bridge in series in the circuit of the controller for the bridge traversing motor, it is not possible to operate the bridge untll both of these clamp mechanisms have been opened.

While I have shown and described a preterrcd embodiment ot my invention, it will be understood that the invention is not limited to this precise embodiment as it may be otherwise embodied within the scope of the appended claims without departing from the spirit thereof.

I claim:

1. In a rail clampmechanism, a pair of clamp levers adapted to grip the opposite sides ofv a rail, toggle means connected to said levers and including bell crank means, an equalizer connected to said bell crank means, and a pair of springs connected to said equalizer for rocking said levers into engagement with the rail, substantially as described. p j

2. In a rail "clamp mechanism, a pair of clamp levers adapted to grip the opposite sides of a rail, toggle means connected to said levers, means for actuating said toggle means to rock said levers into engagement with the rail, a sheave j ournaled on each lever, a drum,

a cable connecting said drum with said sheaves, and means for rotating said drum to rock said levers out of engagement with the rail, substantially as described.

3.1m rail clamp mechanism, two pairs of i clamp levers adapted to grip a rail at spaced points, and separate toggle means operatively connected to each pair of levers, spring means associated with each toggle means for applying the rail-gripping force to the clamp levers," a drum, cable means connecting the drum with the two pairs of clamp levers, and means for rotating said drum to rock said clamp levers out, of engagementwith the rail and put said spring means under tension, the

toggle means being so arranged that the mechanical advantage of the toggle varies inversely-with the power otth'e spring, substantially as described. r i

l. In a rail clamp mechanism, a-pair cit clamp levers adapted to grip the opposite sides of arail, a bell-crank lever pivoted to one of said clamp levers, a link connecting one other clamp lever and constituting with said arma toggle, spring means connected to the other arm of said bell-crank lever for ap plying the rail-gripping force to said clamp levers, a sheave journa-led on the upper end of each clamp lever, a. drum, cable connected at one end to the drum and at the other end to the upper end of one of said'clamp l vers and'passing around said sheaves, and means for rotating said drum to rock said clamp levers out of engagementwith the rail and place said spring means under tension and for holding said drum in said position, substantially as described. I

6. In a rail clamp mechanism, a pair of vertically extending clamp levers-pivoted adj acent their lower ends and having gripping jaws at saidlower ends adapted to grip the opposite sides of a rail, one of said clamp leversbeing pivoted adjacent its upper end and having a bell-crank lever pivoted there to adjacent said upper end, a link connecting one arm of said bell-crank lever with the other clamp lever and constituting with said arm a toggle, and spring means connected to the other arm of said bell-crank lever for applying the rail-gripping force" to said clamp levers, substantially as described.

7. In a rail clamp mechanism, a pair'of clamp levers adapted to grip the opposite sides of a rail, toggle means connected to said levers, an equalizer connected to said toggle means, and a pair of springs connected to said equalizer tor rocking said levers into engagement with the rail, substantially as described. f v

In a rail clamp mechanismfor traveling structures, a pair oi clamp levers adapted to grip the opposite sides of a rail, spring means 'for applying the full effective rail gripping torceto said levers independently of any movement of said'structure along the rail, means for multiplying the power applie'dbythe spring means to the levers, and mean's'for rocking said levers out of engage mentwith the 'rail,said means comprising a my hand.

drum, a sheave journaled on each lever and a cable connecting said drum with said sheaves, substantially as described.

9. A rail clamp, comprising a movable clamp jaw, a toggle operatively connected thereto, a spring tending to operate the toggle'and thus move the clamp jaw against the rail, and opening means for operating the toggle in areverse direction to clear the clamp jaw of the rail, the toggle and the opening means being so arranged that the force required for opposing the spring and holding the clamp jaw in open position decreases after the aw is opened, substantially as described.

10. A rail clamp mechanism, comprising clamping jaws, springs for setting the clamping jaws, a connection between the springs and the jaws, and means torpositively limiting the range of effective action of the springs on the connec ion and holding the springs under load, substantially as described.

11. A rail clamp mechanism, comprising clamping jaws, springs for setting the clamping jaws, a connection between the springs and thejaws, and means for holding the springs underload to permit adjustment 01 the connection, substantially as described.

12. A rail clamp mechanism, comprising a clamp jaw, a spring for setting the clamping jaw, a member movable by the spring and adapted to transmit force supplied by said spring, a connection between the member and the clamping jaw, and means for limiting the movement of said member so as tomainin the spring under load, substantially as described.

13. A rail clamp comprising a clamping jaw, a spring for actuating the jaw, a frame member against which the spring is biased, the frame member having an opening therein, a rod extending through the opening, and stop on the rod eliective for engaging that portion of the-frame member adjacent the opening and limiting the movement of the spring. V

' 14:. A rail clamp comprising a clamp, a plurality of springs for actuating the same, a frame member against which the springs are biased, the frame member having openings therein, an equalizing linkage having portions extending through the openings and making operative connections with the springs, and stops engaged by'th'ose portions of the frame member adjacent the openings for limiting the movements of the springs.

In testimony w ereoi I'have hereunto set BERNA D n. KERSTING. 

